Moth-eaten Statistics: A Reply to Kenneth R. Miller

by Jonathan Wells

British statesman Benjamin Disraeli is reputed to have said that there are
lies, damn lies, and statistics. Statistics based on unbiased samples
and rigorous analyses can point us in the direction of the truth; but statistics
can also be unscrupulously manipulated to prove things that are
patently untrue. Brown University biology professor Kenneth R. Miller demonstrates
the latter in his most recent response to me:

The relative proportions of light-colored and dark-colored (melanic)
peppered moths changed during the industrial revolution, supposedly because
of camouflage and bird predation. In the early 1950s, British physician Bernard
Kettlewell released captive moths onto nearby tree trunks and made observations
that seemed to confirm this explanation. Many biology textbooks now use Kettlewells
work on industrial melanism as the classic demonstration of Darwinian natural
selection in action, and they typically illustrate the story with photos of
moths on tree trunks. Yet biologists in the 1980s discovered that peppered moths
rarely rest on tree trunks in the wild. The textbook photos are staged, and
in 2000 I criticized this practice in my book, Icons of Evolution.